Plant systems for nuclear reactor applications, such as reactor fuel vessels, reactor fuel coolant, conduits and related components contain liquids or stream at high temperature and high pressure. In addition, such systems can contain solid and liquid materials emitting neutrons, x-rays and gamma ray radiation.
Historically, separate products have been used to provide thermal insulation and radiation shielding. In addition, thermal insulations are permanently installed onto the systems while ionized radiation shielding commonly has been installed temporarily during plant outage and removed thereafter. Because only temporary shieldings have been in use, the current practice in the industry has been to undergo a chemical decontamination process before an outage. This process is performed to reduce the amount of ionized radiation emanating from a system in order to reduce radiation exposure to personnel working therein and thereinaround. This chemical decontamination process is an added operation and maintenance cost.
From a regulatory plant design and qualification process, all structures attached to a safety-related plant system on a permanent basis must satisfy a number of regulatory concerns, such as seismic (earthquake) qualification, fire loading and material interaction with stainless steel.
Also, most effective shielding designs are relatively heavy so that the design of any structures bearing this weight must be carefully evaluated.